Hillsboro, OR -

An 18-year-old man who took the SUV to a car wash after his girlfriend ran over two young girls playing in leaves in Forest Grove pleaded guilty to hindering prosecution and was sentenced Thursday in a Washington County court to 13 months in prison.

Mario Echeverria was a passenger in the car his girlfriend, Cinthya Garcia-Cisneros, drove through a pile of leaves Oct. 20. The accident killed two stepsisters, 6 and 11 years old.

After learning of the deaths, Echeverria took the SUV to a Hillsboro car wash the next day to remove evidence.

The Oregonian reports the 18-year-old Garcia-Cisneros has pleaded not guilty to felony hit-and-run, and her trial is scheduled for next month.